Wicking dynamics in yarns.

ABSTRACT

The spontaneous imbibition of a liquid within porous media, known as wicking, can display uncommon features in textiles and yarns. Yarns exhibited step-wise wicking dynamics not captured by current models. HYPOTHESIS: Wicking dynamics in yarns not only depend on inter-fiber pore filling, but are mainly determined by the pore-to-pore transition processes and the structure of the pore network. EXPERIMENTS Fast X-ray tomographic microscopy is employed to reveal the pore scale processes and neutron radiography for the macroscopic water uptake in yarns. A semi-empirical pore network model is presented that employs the measured pore network topology and pore scale dynamics to reproduce the experimentally observed wicking dynamics in yarns. FINDINGS: The yarn pore system is a sparse network of long and narrow pores that promotes step-wise uptake dynamics. Wicking in yarns displays fast pore filling events in the order of seconds and long waiting times between filling events up to several minutes while navigating the pore network. As main result, we find that a few filling events directly determine the macroscopic behavior of wicking in the sparse pore network of yarns. It is necessary to consider pore-to-pore transition waiting times and the pore network structure to explain the characteristics of wicking dynamics in yarns.